1. Field of the Invention
The present invention relates to an electrophotographic photosensitive member formed with having a photosensitive layer formed on an outer circumference of a cylindrical body, and an image forming apparatus utilizing electrophotographic method and provided with the electrophotographic photosensitive member.
2. Description of the Related Art
The electrophotographic photosensitive member includes a cylindrical body having an outer circumference formed withon which a photosensitive layer is formed. In such an electrophotographic photosensitive member, since film texture and adhesiveness of the photosensitive layer affects the image property, it is important to adjust them for enhancing improving the image property.
Meanwhile, the film texture and the adhesiveness of the photosensitive layer are affected by surface roughness of the cylindrical body. For example, when making an electrophotographic photosensitive member by forming a photosensitive layer on a surface of a cylindrical body with a relatively large surface roughness, irregularities on the surface of the cylindrical body appear on images and cause roughness of images. Further, when the surface roughness of the cylindrical body is relatively large, anomalous growth in film forming process is generated, which may cause problem such as charge leakage (refer to JP-A-2005-141120, for example).
On the other hand, when making the cylindrical body to have a relatively small surface roughness, the problems caused due to large surface roughness are solved, however, since the adhesiveness of the photosensitive layer relative to the cylindrical body is lowered, peeling of film is likely to be generated. Since mechanical load tends to be applied at the end portions of the electrophotographic photosensitive member, peeling of film is more likely to be generated at the end portions of the electrophotographic photosensitive member. Though the end portions of the electrophotographic photosensitive member does not contribute to image forming, if the peeling of film generated at the end portions extends to the image forming area, the image property may be affected.
Recent years, demand for images of colored colorization, higher quality, and higher speed of images has been increased, and it became mainstream to use amorphous silicon (a-Si) material for the make the photosensitive layers and aluminum for the cylindrical body of amorphous silicon (a-Si) and aluminum, respectively. In this case, a difference in inner stress (or rate of thermal expansion) of between the photosensitive layer and the cylindrical body tends to be increased, so that peeling of film at the outer circumference is more likely to be generated when the surface roughness of the outer circumference of the cylindrical body is relatively small.
As a result, improvement of the image property by adjusting optimizing the film texture and the adhesiveness of the photosensitive layer is limited, and thus cannot sufficiently meet the recent demand for colorization, higher quality, and higher speed of images only by changing the surface roughness of the outer surface of the cylindrical body has limitation in enhancing the image property, and thus cannot reliably meet the recent demand for images of colored, high quality, and high speed.